advent_of_code_2024/Level5/Level5Solver.cs

namespace AoC24;

using AoC24.Common;
using AoCLevelInputProvider;
using Parsing;
using Parsing.Schema;

public class Rule
{
    public string NumLeft { get; set; }
    public string NumRight { get; set; }

    public Rule(string numLeft, string numRight)
    {
        NumLeft = numLeft;
        NumRight = numRight;
    }

    public bool IsApplicable(List<string> inputs)
    {
        return inputs.Contains(NumLeft) && inputs.Contains(NumRight);
    }

    public bool IsValid(List<string> inputs)
    {
        if(!IsApplicable(inputs))
        {
            return true;
        }
        for(int i = 0; i < inputs.Count; i++)
        {
            if(inputs[i].Equals(NumRight))
            {
                //Console.WriteLine("Matched NumRight:" + inputs[i]);
                return false;
            }
            if(inputs[i].Equals(NumLeft))
            {
                //Console.WriteLine("Matched NumLeft:" + inputs[i]);
                return true;
            }
        }
        return true;
    }
}

public class RuleSet
{
    public List<Rule> Rules { get; set; } = new List<Rule>();

    public RuleSet()
    {}

    public bool IsValid(List<string> inputs)
    {
        foreach(var rule in Rules)
        {
            if(!rule.IsValid(inputs))
            {
                return false;
            }
        }
        return true;
    }
}

public class RuleOrderer
{
    private List<Rule> rules;

    public RuleOrderer(List<Rule> rules)
    {
        this.rules = rules;
    }

    public bool RuleExistsThatPutsThisPageFirst(string page, string pageToCompareTo)
    {
        foreach (var rule in rules)
        {
            if(rule.NumLeft == page && rule.NumRight == pageToCompareTo)
            {
                return true;
            }
        }
        return false;
    }

    public List<string> OrderViaRules(List<string> input)
    {
        var sortedList = new List<string>();

        foreach(string num in input)
        {
            if(sortedList.Count == 0)
            {
                sortedList.Add(num);
            }
            else
            {
                for(int i = 0; i < sortedList.Count; i++)
                {
                    var compareNum = sortedList[i];
                    if(this.RuleExistsThatPutsThisPageFirst(num, compareNum))
                    {
                        sortedList.Insert(i, num);
                        //Console.WriteLine(string.Join(",", sortedList));
                        break;
                    }
                    if( i == sortedList.Count - 1)
                    {
                        sortedList.Add(num);
                        //Console.WriteLine(string.Join(",", sortedList));
                        break;
                    }
                }
            }
        }

        // Console.WriteLine("=================");
        // Console.WriteLine("Input: " + string.Join(",", input));
        // Console.WriteLine("Applicable rules: ");
        // foreach(var rule in rules.ToList().OrderBy(x => x.NumLeft))
        // {
        //     Console.WriteLine(rule.NumLeft + "|" + rule.NumRight);
        // }
        // Console.WriteLine("Output: " + string.Join(",", sortedList));
        // Console.ReadLine();

        return sortedList;  
    }
}

public class Level5Solver: FragmentLevelSolverBase
{
    public override int LevelNumber
    {
        get { return 5; }
    }

    protected override FragmentSchemaBuilder DefineInputSchema(FragmentSchemaBuilder schemaBuilder)
    {
        return schemaBuilder
                    .StartOptions()
                        .Option()
                            .Expect(InputType.Integer, "rule_left")
                            .Expect("|")
                            .Expect(InputType.Integer, "rule_right")
                        .Option()
                            .Expect(InputType.Integer, "pages")
                            .Repeat()
                                .Expect(",")
                                .Expect(InputType.Integer, "pages")
                            .EndRepetition()
                    .EndOptions();
    }

    public override string SolveFirstStar()
    {
        var data = this.GetData()
                       .AsFragments();

        var validSequences = new List<List<string>>();
        var ruleset = new RuleSet();

        foreach(var fragment in data)
        {
            if(fragment["rule_left"].Count > 0)
            {
                //Console.WriteLine("Adding rule: " + fragment["rule_left"][0] + "|" + fragment["rule_right"][0]);
                ruleset.Rules.Add(new Rule(fragment["rule_left"][0], fragment["rule_right"][0]));
            }
            else
            {
                //Console.WriteLine(string.Join(",", fragment["pages"]));
                if(ruleset.IsValid(fragment["pages"]))
                {
                    //Console.WriteLine("Adding fragment: " + string.Join(",", fragment["pages"]));
                    validSequences.Add(fragment["pages"]);
                }
            }
        }

        var count = 0;

        foreach(var sequence in validSequences)
        {
            var middleItem = sequence[sequence.Count/2];
            count += int.Parse(middleItem);
        }

        return count.ToString();
    }

    public override string SolveSecondStar()
    {
        var data = this.GetData()
                        .AsFragments();

        var invalidSequences = new List<List<string>>();
        var ruleset = new RuleSet();

        foreach(var fragment in data)
        {
            if(fragment["rule_left"].Count > 0)
            {
                //Console.WriteLine("Adding rule: " + fragment["rule_left"][0] + "|" + fragment["rule_right"][0]);
                ruleset.Rules.Add(new Rule(fragment["rule_left"][0], fragment["rule_right"][0]));
            }
            else
            {
                //Console.WriteLine(string.Join(",", fragment["pages"]));
                if(!ruleset.IsValid(fragment["pages"]))
                {
                    //Console.WriteLine("Adding fragment: " + string.Join(",", fragment["pages"]));
                    invalidSequences.Add(fragment["pages"]);
                }
            }
        }

        var orderedSequences = new List<List<string>>();

        foreach(var sequence in invalidSequences)
        {
            var applicableRules = new List<Rule>();
            foreach(var rule in ruleset.Rules)
            {
                if(rule.IsApplicable(sequence))
                {
                    applicableRules.Add(rule);
                }
            }

            var orderer = new RuleOrderer(applicableRules);
            var orderedSequence = orderer.OrderViaRules(sequence);
            if(!ruleset.IsValid(orderedSequence))
            {
                throw new Exception("badbadbad");
            }
            orderedSequences.Add(orderedSequence);
        }

        var count = 0;

        foreach(var sequence in orderedSequences)
        {
            var middleItem = sequence[sequence.Count/2];
            count += int.Parse(middleItem);
        }

        return count.ToString();
    }
}